Teach to your ipod!!!!

Allright, so I tested my ipod's battery by playing 1 hour to sims 3 while it was on 60%, and instead of 1hour IT LAST NEAR 5/10 MINUTES MORE!!! MY IPOD AINT SCRAP!!! but what's still makin me poop, is the bad reading/calculating of the battery... keeps decharging rapidetly during 80% and it last 1 hour to 20%, is there any way to make the ipod read the battery to a regular speed? does not decharge faster than another %